1. Field of the Invention
Aspects of the present invention relate to the Universal Plug and Play (UPnP) standard, and more particularly, to a method and apparatus for efficiently transmitting and receiving information regarding a UPnP event.
2. Description of the Related Art
Since a personal computer (PC) can automatically recognize peripherals using a Plug and Play function, a user can easily install peripherals. UPnP is a technique of extending the Plug and Play function all over a network and allows devices (PCs, peripherals, home appliances, etc.) to automatically recognize each other when they are connected to the network. According to the UPnP standard, network devices are largely classified into controlled devices (CD) and control points (CP). A CD, which is also referred to just as a device, provides a service, and, a CP controls the CD to use the service.
FIG. 1 is a diagram illustrating operations of UPnP networking. Referring to FIG. 1, UPnP networking includes an addressing operation 11, a discovery operation 12, a description operation 13, a control operation 14, an eventing operation 15, and a presentation operation 16.
In the addressing operation 11, the IP addresses of UPnP network devices (a device and a CP) are designated according to an automatic Internet protocol (Auto IP) method or a Dynamic Host Configuration Protocol (DHCP) client method.
In the discovery operation 12, the CP detects the device over a network according to a Simple Service Discovery Protocol (SSDP) after the IP addresses of the device and the CP are designated in addressing operation 11.
In the description operation 13, if the CP detects the device over the network in the discovery operation 12, the CP obtains a description regarding the device to determine the service that the device will provide.
In the control operation 14, if the CP obtains the description of the device in the description operation 13, the CP controls the device by calling an action according to a Simple Object Access Protocol (SOAP), based on the description of the device.
In the eventing operation 15, the device transmits an event message to indicate that at least one of the statuses of the service has changed, according to a Generic Event Notification Architecture (GENA).
In the presentation operation 16, the CP is connected to a presentation Uniform Resource Locator (URL) of the device in order to provide a user with a presentation of the device. Therefore, the user can control the device or recognize the current status of the device using the presentation URL of the device.
FIG. 2 is a diagram illustrating operations in a conventional UPnP eventing process. Referring to FIG. 2, the conventional UPnP eventing process includes the following operations.
First, in order to learn of a change in service that a device 2 provides, a CP 1 transmits to the device 2 an event subscription request message requesting a subscription to an event that indicates a change in service. Next, after receiving the event subscription request message from the CP 1, the device 2 transmits to the CP 1 an event subscription response message indicating that the CP I has subscribed to the event successfully.
Next, the device 2 transmits an initial event message that contains current values of status parameters indicating statuses of the service. Next, when an event occurs due to a status change of at least one of the services, the device 2 transmits an event message that contains the current values of the status parameters indicating the statuses of the service to the CP 1 subscribing to the event.
As described above, conventionally, if the status of at least one of the service of the device 2 changes, the device 2 transmits an event in units of service. Then, all of CPs subscribing to the event that indicates a status change of each service, receive an event message that contains information regarding the statuses of the service, i.e., the current values of all of a plurality of status parameters thereof.
That is, each control point may receive even an event message containing unnecessary status parameters. In this case, the control point filters the event message or a specific status parameter, thereby increasing network traffic and the load on the control point. In particular, this problem becomes more serious in the case of a home network with a narrow bandwidth or a control point with low hardware performance.